It is structurally impossible to avoid gas leaks from flange parts or valve parts of piping in a plant. In a large plant, which requires long running time, the production is continued with follow-up observations while gas is leaking, as long as effects on the environment are small and do not cause problems, and the maintenance such as part replacements is carried out while the production is suspended in the regular or irregular repairs.
This is based on the idea of ALARP (As Low As Reasonably Practicable), to eliminate accidents reasonably while suppressing excessive facility investments, which is referred to in the “Guidelines for Investigation of Danger or Toxicity, etc. (commonly known as “risk assessment guidelines”) and Instructions thereof,” p. 24, by Safety Division, Industrial Safety and Health Department, Ministry of Health, Labour, and Welfare, March 2006.
However, it has been necessary for the operators to make rounds for follow-up observations, and there has been no means to manage the state of leakage quantitatively, continuously and collectively. The repairs and the following planning for production and marketing based on the unreliable information are not reasonable enough, requiring the excessive safety margin.
In the patent document 1, described is a system to make a diagnosis for predictive maintenance by analysis of the physical parameters with values indicating the operational state of machine.
In the patent document 2, described is a system to make a diagnosis for predictive maintenance with reference to the parameters indicating the operational state and, if needed, communicate with the remote administrative computer so that the administrator diagnoses in detail.